According to the current Standards of the American Association of Blood Banks (AABB), any unit of blood to be frozen prior to storage must be frozen within six days of collection from the donor. This restrictiion is due in part to the low levels of 2,3 diphosphoglycerate (2,3 DPG) in red cells stored in standard anticoagulants for more than six days. It is often desirable, however, to freeze units of red blood cells after the six day limit. New anticoagulant/preservative solutions are now under study which maintain higher levels of 2,3 DPG in the liquid stored red cells (AS-4 and AS-5, Cutter Biological, Berkeley, California). We wish to study the post-thaw, post-transfusion survival of units stored as liquid in these solutions as well as standard anticoagulants for varying lengths of time prior to freezing. A unit will be drawn from a normal, nonpregnant adult volunteer in a currently licensed anticoagulant/preservative or in a high 2,3 DPG solution. After liquid storage to either the midpoint or the endpoint of maximum allowable time, an aliquot of red cells will be removed from the unit and a 51chromium survival study will be performed. The unit will then be frozen for eight weeks, thawed, and survival studies performed. Hematologic studies and determinations of adenosine triphosphate (ATP) and 2,3 DPG will be performed on the red cells at the time of both survival studies.